


Synesthesia

by OneOfThoseThings



Series: Interspecies Compatibility [7]
Category: Doctor Who (2005)
Genre: Alien Gender/Sexuality, Alien/Human Relationships, Angst and Fluff and Smut, F/M, Friends With Benefits, Interspecies Relationship(s), Mutual Masturbation (Basically), Porn With Plot, Some Humor, Telepathic Sex (Sort Of), Telepathic Transference, Telepathy, no beta we die like men
Language: English
Status: Completed
Published: 2020-02-24
Updated: 2020-02-24
Packaged: 2021-02-28 06:02:28
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 4,006
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22879162
Author URL: https://archiveofourown.org/users/OneOfThoseThings/pseuds/OneOfThoseThings
Summary: Donna and the Doctor have some communication difficulties. Then they have some very successful communications. Then they communicate a little too successfully and the Doctor gets an unexpected taste of a particularly strong human reaction. It's a bit much.(Part of the Interspecies Compatibility series, but can be read on its own if one has a high tolerance for accepting headcanon and a low tolerance for reading backstory.)
Relationships: Tenth Doctor/Donna Noble
Series: Interspecies Compatibility [7]
Series URL: https://archiveofourown.org/series/1637608
Comments: 22
Kudos: 133





	1. Part the First

**Author's Note:**

> Synesthesia (ala Wikipedia): A perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway.

Admittedly, the Doctor had forgotten some minor details about the cultural revolution of the Terran outposts of the 35th century. It was _a bit_ more sexual in nature than he remembered. But to be fair, it was a human affair and it was honestly harder to find a time when humans _weren’t_ rambling on about sex than it was to accidentally stumble into a minor recalibration of the mores surrounding such things.

Naturally, Donna was being completely unreasonable about the whole thing. 

“You took me to a flipping orgy! This is a flipping orgy!!” She was quite stuck on that particular word. 

“It’s a cultural revolution,” he reminded her. “Run by humans. There’s bound to be some element of…” He gestured vaguely. “…connectivity.” 

Donna glared at him like he’d personally arranged it, for the express purpose of irritating her. 

He herded her toward the main hall. “Now then, why don’t you go have a mingle while I look into that first edition book.” 

Donna’s brows shot into her hairline. “You want me to go off on my own? Right now?”

He looked over the crowd, trying to see the problem with that suggestion. “No one is behaving aggressively. It’s basically a party with a unique dress code. And other humans! Aren’t you always going on about how much you miss other humans? Well, here’s your chance to catch up on that.” He made a subtle shooing motion. “Interact away!” 

Donna cycled through several facial expressions too quickly for him to read and landed on something that looked slightly affronted and deeply indignant. “This isn’t doggy day care, you know! You can’t just drop me off with a pat to the head and come collect me later!” 

He frowned, “Which part of that do you feel is infeasible? I’m sure I’ll be able to locate you. For one thing, you’re noticeably more clothed than most of the locals.” 

Donna pressed her mouth into a thin line. “You know what?! Fine!! Off I go! Hope you have a good picture for the ‘Missing’ posters later!” She flounced off, grumbling to herself. 

The Doctor left her to it, much more interested in that tome that should be newly published by that date. “Xing” was considered to be a premier work of human erotica, and the science held up for centuries, without any major disputes. 

He might have accidentally left the specific subject matter out of his pitch to Donna. 

The Doctor was more than confident in his technical knowledge of human anatomy, but he suspected that he was not as advanced in his knowledge or practice of coupling peripherals.  It didn’t take a telepath to tell that Donna was getting a little restless in their physical sessions. She was strangely defensive about the whole thing, apparently hardwired to assume that any efforts to improve implied criticism of one or both parties involved. 

Unable to suss out direct feedback, he obviously needed to expand his research. 

He set off toward the lyceum, already working through a mental checklist to cross-index. 

* * *

The Doctor made quick work of the tome and its corollaries. Three hours, sixteen minutes, and four seconds later, he was loaded up with several centuries worth of new knowledge and more than a few ideas about potential practical applications. 

The first (key) ingredient would be Donna, so he set off to find her. 

It was as easy as he’d expected. She was not exactly designed to blend in with the crowd. He found her cozied up with two of the locals, likely complimenting one of them on the melanin levels of his skin. She had both hands on his bare arms, moving up and down.

It made sense that she’d be interested. She had almost no melanin to speak of.

“Donna!” He hopped over the back of the divider, easily inserting himself in the alcove. “I told you I wouldn’t be long. Made some new friends, have you? Hello, I’m the Doctor.” He held out a hand, cheerily. After a pause, the nearest man took one large hand from Donna’s collar and slowly shook the Doctor’s. 

“Kav,” he said, in a low, rumbling voice. 

The other man was half wedged behind Donna for some reason and didn’t seem to be able to reach over so he substituted a nod. “Taz.”

The Doctor smiled. “Nice to meet you, Kav and Taz.” He redirected his attention to Donna. “Now then, shall we head off? I’ve completed my research, you might be interested to know.” 

Donna didn’t look interested. In fact, she looked slightly vexed. “Oh, look who it is― my handler! Is it feeding time already?”

Definitely vexed. 

Kav and Taz stilled, clearly sensing danger. 

“Oh, you don’t have to stop,” Donna said. “He doesn’t care about any of this. We’re all just gerbils in pants to him.” 

The Doctor frowned, “Are you angry with me?” 

“Oh, no!” she crowed. “Why would I possibly be angry?! I love being dropped off in the middle of strange cities like an inconvenient stray! I feel fantastic! _Let’s go flipping dancing!!_ ” 

She jumped to her feet, shoving past him with a muttered apology to her abandoned conversation partners. 

The Doctor followed, trying to work out where the communication lines must be failing. 

“I thought you _liked_ spending time with other humans…”

Donna whirled on him, furious, “Are you gearing up to send me home? Is that what this is?!” 

The Doctor balked, “What?! No!!” His hearts clenched. “Do you― Is that what you want?”

“Of course not!” she squawked. Contrarily, that assertion only seemed to make her madder. “But that doesn’t mean you can just boot me to the curb when you get bored!” 

The Doctor was still trying to get over what he was pretty sure was a mild cardiac event, and it took him a few beats to decode that. “Is that why you’re angry? You think I planned this trip as a distraction so I could, what, hang out on my own??”

Donna crossed her arms. “Well… yeah!”

The Doctor was not an idiot. He knew that the appropriate response to that was not to laugh. He was well aware that Donna was upset and that the absolute last thing he should do was laugh at that.

A choked hysterical sound slipped out of him, followed by another involuntary burst, much more easily identified as a laugh. 

Donna looked, in a word, apoplectic. 

And just like that he was off. He doubled over, laughing so hard his ribs hurt and his lungs ached. Donna’s wildly indignant expression just sent him over again and again. 

“Oi!” Donna sputtered. When that failed to work, she got louder. “Oi!!” 

The Doctor sucked in air, trying to regain control over that, at the very least. He managed to taper down to slightly hysterical giggles, wiping his eyes. When he could finally see well enough, he looked up to find Donna gawking like she couldn’t decide whether to be horrified or furious or just join in laughing. 

“Donna Noble,” he wheezed, “How could I get _bored_ of _you_?” 

Her expression twisted and pinched before landing on something between disbelieving and deeply judgmental. “You. Are. Bonkers.”

He made an embarrassingly happy sound in the back of his throat, braced his hands on his knees and managed to force himself upright. “Ahhh, Donna. What would I do without you?” He slung an arm over her shoulders, wiping his eyes with his other hand. 

Donna, grumbled, but didn’t hit him. She looked quite pleased, actually, but was obviously trying not to let that show. 

Two strands of hair had come loose from her half-pinned twist. He reached over and carefully tucked them behind her ear. She gave him an odd, furtive look out of the corner of her eye. Her shoulders moved stiffly under his arm. 

“Well,” she said, tone brisk. “What _were_ you doing all day, if my guess is so bleeding hysterically off-base?”

“Research,” he answered, already scanning the area for an optimal location. “Like I said.” 

She slanted an annoyed look up at him. “Research on _what_?”

He gave her a quick once-over. She looked vaguely irritated, but no more than usual. And she still hadn’t shrugged his arm off her shoulders. “I could show you,” he offered.

Donna turned her head to make sure he got the full force of her skeptical squint. “How exactly would you―“ She cut off with a squeak as he abruptly dropped the hand on her shoulder to the back of her neck, pulling her head back and slamming his mouth into hers with bruising force. 


	2. Part the Second (NSFW)

The Doctor shoved Donna backwards the few crucial meters to a nearby niche, just barely out of sight of the general population.

Donna made a series of escalating sounds as her back hit the wall, his chest hit her chest, and his knee thrust between hers. Her hands fisted in his jacket, but she seemed to be pulling him closer, not pushing him back. 

He clenched his hand in her hair, and yanked her head back so that he could move his attention to the junction of her ear and jaw. 

“Holy hell!” Donna gasped, “What kind of book were you reading?!” 

“An informative one,” he said, puffing air on the shell of her ear and feeling her full-bodied shudder. “Added some social to the science,” he drew out the s’s, and her shivers became nearly violent. 

Donna made some entirely new noises as he hitched the leg between hers ten centimeters higher. 

“Spontaneity, for example,” he moved his mouth down to the junction of her neck and shoulder. “A bit of exhibitionism.” He licked her pulse point, feeling it jump in response. “You show all the classic markers of someone who likes a bit of exhibitionism.” Her pulse jumped again, hard enough for him to feel it against his chest as well. 

“I’m sure I don’t know what you mean by that,” Donna groaned, grinding shamelessly on his leg. 

He dropped one hand to her trousers, manipulating them open but not down, working his hand inside.

This part he was reasonably confident in. He could feel her reactions in the pads of each finger, vibrating like a finely-tuned instrument. He moved his thumb in slow, firm circles, coaxing the proper resonance.

“Can you― ah― can you do the thing, one-handed?” Donna gasped, barely coherent. 

He curled his fingers. “Is that some sort of riddle?” 

She jerked, simultaneously trying to gain and relieve pressure. “N-not that! The― mind thing! _Your_ thing!” 

He paused, thinking, and she immediately started the most interesting mix of whining and whimpering until he absently resumed flexing his fingers. “No idea,” he admitted. 

“Think you can try it _without_ stopping?” She ground down, emphatically. 

“Honestly, I have no idea.” 

She made a frustrated keening noise, curling her lips back and baring her teeth. “Can. You. Try. To. Guess.”

He ran a quick assessment. His hand was working more on muscle memory than active effort. His position was fairly steady, mostly pinning her with his weight. “75% probability that I could manage that,” he said, trying not to show any interest one way or another. 

“Fine. I’ll take those odds.” Donna gritted out between her teeth. “But if you stop, I’m calling off _both_ our rides.” In spite of her tone, she had that anticipatory look of someone who'd discovered something _marvelous_ and was just dying to share it. 

He slipped his fingers in again and tried to focus on the rhythm, even as his other hand came up to her temple. 

~*~

Her mind twisted around him, writhing in impossible endless knots. A deep aching _want_ broiled through every sensation, heightening sound and touch and taste until it felt like he would drown. 

Donna shifted against him, seeking more contact, more friction, more everything, and he could feel it through her, like drinking and drinking only to get thirstier with each gulp. When he clenched his fingers in response, the feedback loop was blinding. 

Her mind overwhelmed his, pulling him deeper within herself as her body tried to do the same. 

Something deep and red and urgent bloomed, seeping into every corner, every crevice.

His fingers moved over and within her, sparking thrilling chains of reactions. And somewhere deep within the writhing, burning mass of sensation, something cracked open.

Donna cried out and her senses flooded crimson and sparked pure white. 

~*~

He blinked his eyes open, but the storm didn’t stop. His blood was boiling and singing and burning and he couldn’t seem to get enough air. 

Donna was talking, he realized. He couldn’t make out the words. 

She stroked the back of his head, her nails catching in the short hairs, and he jerked back just far enough to focus. 

Whatever she saw in his expression, it was swallowed by her eyes, wider than moons. 

She was still talking. Her mouth moved, but the sounds were carried off by the wind swirling in his own ears. He tried to focus, putting every ounce of energy into the effort. One word made it through the maelstrom. 

“TARDIS.” 


	3. Part the Third

By the time the Doctor stumbled into the TARDIS, the wave of secondary sensations had become simultaneously better and much, much worse. He could hear every sound, see every color, all at the same time, overloading his receptors. 

The TARDIS thrummed and he felt it in every nerve ending, but it also helped him focus. 

“Oh, that’s better,” he took a deep breath, and then another one. 

Donna’s voice came into range, speaking very quickly. 

“Okay, here we go, easy does it…” She coaxed him onto the jump seat with her hands hovering, not quite touching. “There we are!” she said, far too brightly. She leaned in, checking his pupils. “How are we feeling? Bit better?” 

He felt like he was running on electric lava. “Yeah,” he managed, “ _Brilliant._ ” The consonants rolled on his tongue, and even that was delicious. “No wonder you’re always on about this.” He shifted slowly, feeling every inch of fabric where it pulled across every inch of skin. 

Donna barked out a laugh, high and a bit hysterical, but relieved. “Yeah, bit of a game changer, isn’t it?” She ruffled his hair.

The contact sent his senses screaming for more and less and more, more, _more_. 

“Oooh-ookhay,” he groaned, as all the muscles in his neck seemed to give out. “Think this might have lingering effects.” 

Donna snatched her hand back, immediately crossing her arms. “Sorry!”

The Doctor clenched his teeth until his jaw ached, trying to refocus. “’Sok. Might just need a mo’.” He stared up at the TARDIS ceiling with wide eyes before forcing himself upright to shift into flight. As soon as he hit the dematerialization switch, the TARDIS lurched, knocking him off his feet and he was not proud of the sound he made when Donna knocked into him from behind. 

He felt the impact like a flashbulb in the back of his eyes, heard it singing in his ears. 

“Sorry! Sorry! Sorry!” She sprang back, gripping the railing. 

“It’s fine; I’m fine,” he gritted out, “Just a little ah, sensitized.” He stood up, carefully. “Think I might head to the Zero Room for a bit.” 

“Right, sure. Zero Room. Is that a location or a level or… Is it like a hotel? Are there numbers on the doors? I haven’t noticed numbers. What number is my room?” Donna fluttered around him, adding to the background noise. 

“Donna,” he said, very slowly. “I think it might be best if I went alone.” 

Donna stuttered in her circling, pulling back a hand that was hovering near his elbow. “Right. Yes. Yeah. Makes sense.” She went quiet for exactly three heartsbeats. “Are you sure? Do you want me to, uh, help? I could help, if you―“ 

She was suddenly too bright for him to look at directly. He forced himself to say, “I don’t think that’s a good idea.”

“No, sure, yeah. Course. Bit like I dosed you, isn’t it? Not that I did it on purpose! I did say sorry, didn’t I?” 

“You don’t have to apologize.” It felt like a very strange thing to apologize for. Every single one of his cells sang, and it was all too much and somehow not enough. He wanted― he didn’t even know what he wanted. Just that he _wanted something_. And he just _knew_ Donna would know what, but he couldn’t just― “I’m just going to―“ One foot in front of the other, he forced his legs to carry him to the Zero Room.


	4. Part the Fourth

Sixteen hours, twelve minutes and forty-eight seconds later, the buzzing finally faded from the back of his skull and the Doctor cautiously re-emerged from the Zero Room. 

He immediately headed to the galley, suspecting hydration might be in order. 

Before he could take more than six steps, Donna crashed into the hallway in a flurry of colorful paper airplanes. “What the― Doctor!” She batted away a stray plane, nearly slipping on another. “Oh, you’re up! How are you feeling? Better? Do you want soup or something? What do you eat for this sort of thing? How’s your head?” 

He flinched, just slightly, before he could stop himself and she immediately jumped three feet straight back. 

“Sorry, sorry― I didn’t mean― I did say I was sorry, didn’t I?” 

He huffed, the closest thing he could manage to a laugh. “Yeah, you did. Couple times, there.” He rubbed the back of his neck, “Not your fault though. Didn’t do anything wrong, did you? _I'm_ sorry, by the way. I didn’t mean to alarm you…” 

Donna laughed, just a little too high and loud. “Why would I find any of that alarming? Perfectly normal day, really.” In spite of her casual tone, she flattened herself against the far wall so that he could get by with as much room as possible between them. "Come on, let’s get some food in you before you have another feelings fit."

“Donna,” he stepped closer, holding out a hand. “Really. It’s fine. I’m fine. Just got a little― well, you know― overwhelmed, let’s say.” 

She eyed his outstretched hand and he wiggled his fingers until she gingerly accepted. 

Fighting down the urge to shout ‘Boo!’ just to see what would happen, he carefully tightened his grip, pulling her to the galley. 

He was starving, he realized. He wasn’t quite sure when he’d last eaten. He started methodically eating his way through every food item he could find that didn't require preparation.

“But you’re okay now?” she asked, watching him collect various food items. “You seemed…”

He didn’t know how she was planning on finishing that sentence, but he was pretty sure he didn’t want to hear it out loud. “I’m fine. Really. Was fine the whole time. Just needed to focus a little. I have to give you credit, if that’s how you feel all the time I get why your thoughts seem so scattered. Bit like trying to play cards in a hurricane.” He crunched through a biscuit, searching for crisps. 

“Oi,” Donna said, faintly, and then louder, when she actually resumed paying attention, “Oi!! It’s not _always_ like that! You just can’t hold your brain liquor!” 

He laughed outright, feeling better already. “See, that right there. I’m just impressed you got the words out. Actually, do you need to sit down? How much energy did that take?” 

Donna narrowed her eyes, but the lines of her shoulders relaxed into a more normal position. “Oh, ha, ha, ha... I was right you know. I knew you didn’t know how to do it! You’re such a liar.” 

He scoffed around a banana. “I didn’t lie! I don’t _lie_!” 

“Oh? Let’s see what Protocol 401 has to say about that.” Donna tilted her head back, “Can we have Protocol 401, please?”

A hologram of the Doctor popped up. “This is Emergency Protocol 401. The ice lizards have escaped and are on their way to the apiary. If they―“

“Damn, I meant Protocol 402,” Donna cut it off, “Protocol 402, please!”

The hologram Doctor reset. “This is Protocol 402. I’m not having ‘mind sex’ with you, Donna Noble. Stop asking.”

Donna gestured emphatically. “Well, well, well, would you look at that lying stick-bug in a suit!” 

The Doctor coughed, reminding the TARDIS that Donna was supposed to be locked out of those settings. 

“This feels like a great time for Protocol 612,” Donna said. Then, to the ceiling, “Protocol 612, please!” 

A holographic version of Donna flickered into place and her voice sounded over the speakers. “You really shouldn’t lie so much. You’re terrible at it.”

“Ohhh, how many of those do I have to delete now?” he groaned, reminding the TARDIS _once more_ that this was expressly the sort of thing Donna did not have access to. 

The TARDIS’ lights flickered, and she suggested there might have been a power surge. 

“You were zonked out for most of a day,” Donna shrugged. “Things happened.” 

He glared, crunching a crisp emphatically. “How many?” 

“I’m going to tell you,” Donna said, “But I’m going to tell you like this― There are fewer than 84 new protocols. And just to make things more fun, I was sure to put them in all out of order. One of them might be 116 and one might be 932. But I’ll let you figure all that out. I know how you like your maths. Who was that guy in the leather jacket, by the way?”

“The TARDIS emergency protocols are for emergencies! They’re not here for you to― to― channel surf!” 

Donna shrugged. “Guess you should’ve thought about that before you bricked up my favorite 48th century movies and then took a day-long nap.” 

“I wasn’t napping, I was― It was only sixteen hours! Shouldn’t _you_ have been asleep for at least part of that?” 

“Oh, yeah!” she crowed sarcastically. “That’s what I did the second you hobbled off looking like you were going to shake all your limbs loose and literally fall apart at the seams. I immediately thought, well, that’s that settled! _Off to dreamland!”_

The Doctor sniffed, “No, clearly, you were far too emotionally wrought to do anything other than ferret around in the delicate inner-workings of my time and space ship, chewing through wires and tangling everything up!” He belatedly realized the implications of her previous statement. “Hang on, have you not slept for over 24 hours? Go to sleep! Right now!” 

Donna looked dead on her feet, now that he knew to look for it. She still fought it, stubborn to the last. “No, I’m fine, I―“ she cut off, clearly stifling a yawn. 

“Okay, here we go. Off to bed!” He pulled her up by the elbow.

In spite of her verbal protests, she was completely willing to be guided back to her room and even tucked in like a child. 

“Could you stay?” she mumbled. “Just for a bit. If you don’t― If it’s not―“ 

He toed off his trainers and sat on the other side. “Course I can. Still a bit tired myself. Had a taste of what’s running through your head, didn’t I? No wonder you’re so tired all the time. I’m surprised you don’t go mad with all that. _Welllll_ … Madd _er_.” 

“I have a protocol for this,” Donna mumbled, already more than halfway into her pillow, “I’ll remember which one later.”

He sighed, making yet another mental note to update his firewalls. 

“Speaking of mad…” Donna’s breathing was already evening out, but she kept talking. “Earlier…y’know when you… I had the strangest feeling…” Her voice took on a dreamy tone. “Like standing in a great, endless hall… And it was so quiet…Like it should have been full of voices… But they were all gone… And it was just… empty…” She turned her head, muffling her voice further. "Wonder what that..." 

She trailed off, breathing evening out, and fell asleep. 

The Doctor stared at the ceiling and tried very hard not to think about it. 


End file.
